(a) Field of the Invention
The present invention relates to a light absorptive film adapted to reduce reflection.
(b) Description of the Prior Art
Optical elements such as filters utilizing absorption of light due to metals for shielding or attenuating light are used in various optical systems. Light absorptive films utilizing absorption of light due to metals generally show higher reflectance. Therefore, in optical systems using optical elements such as the above-described light absorptive films, flare or ghost produced by said optical elements may hinder observation. The phase plate used in the phase contrast microscope, for example, is so adapted as to cause phase advance (or phase delay) of .lambda./4 at the ring-like portion on which the zero order diffracted rays are focused and, at the same time, to show adequate absorption as is well known to those skilled in the art. For this purpose, the phase plate is usually evaporation-coated with a metal so as to show absorption. Due to the fact that the metal has a high absorption coefficient and a high reflectance, flare is produced by the reflection and degrades performance of the phase contrast microscopes.